What is breast cancer in men?
A breast cancer is a malignant tumor that starts from cells of the breast. A malignant tumor
is a group of cancer cells that may grow into (invade) surrounding
tissues or spread (metastasize) to distant areas of the body. Breast
cancer occurs mainly in women, but men can get it, too. Many people do
not realize that men have breast tissue and that they can develop breast
cancer.
Normal breast structure
To understand breast cancer, it helps to have some basic knowledge about the normal structure of the breasts.
The breast is made up mainly of lobules (milk-producing glands in
women), ducts (tiny tubes that carry the milk from the lobules to the
nipple), and stroma (fatty tissue and connective tissue surrounding the
ducts and lobules, blood vessels, and lymphatic vessels).
Until puberty (usually around 13 or 14), young boys and girls have a
small amount of breast tissue consisting of a few ducts located under
the nipple and areola (area around the nipple). At puberty, a
girl's ovaries make female hormones, causing breast ducts to grow,
lobules to form at the ends of ducts, and the amount of stroma to
increase. In boys, hormones made by the testicles keep breast tissue
from growing much. Men's breast tissue has ducts, but only a few if any
lobules.
Like all cells of the body, a man's breast duct cells can undergo
cancerous changes. But breast cancer is less common in men because their
breast duct cells are less developed than those of women and because
their breast cells are not constantly exposed to the growth-promoting
effects of female hormones.
The lymph (lymphatic) system of the breast
The lymph system is important to understand because it is one of the
ways that breast cancers can spread. This system has several parts.
Lymph nodes are small, bean-shaped collections of immune system cells
(cells that are important in fighting infections) that are connected by
lymphatic vessels. Lymphatic vessels are like small veins, except that
they carry a clear fluid called lymph (instead of blood) away from the
breast. Lymph contains tissue fluid and waste products, as well as
immune system cells. Breast cancer cells can enter lymphatic vessels and
begin to grow in lymph nodes.
Most lymphatic vessels in the breast connect to lymph nodes under the arm (axillary nodes). Some lymphatic vessels connect to lymph nodes near the breast bone (internal mammary nodes) and either above or below the collarbone (supraclavicular or infraclavicular nodes).
It's important to know if the cancer cells have spread to lymph nodes.
If they have, there is a higher chance that the cells could have gotten
into the bloodstream and spread (metastasized) to other sites in the
body. This is important to know when you are choosing a treatment. The
more lymph nodes with breast cancer cells (positive lymph nodes), the
more likely it is that the cancer might be found in other organs as
well. Still, not all men who have positive lymph nodes develop
metastases, and in some cases a man can have negative lymph nodes and
later develop metastases.
Benign breast conditions
Men can also have some benign (not cancerous) breast disorders.
Benign breast tumors
There are many types of benign breast tumors (abnormal lumps or
masses of tissue), such as papillomas and fibroadenomas. Benign breast
tumors do not spread outside the breast and are not life threatening.
Benign tumors are common in women but are very rare in men.
Gynecomastia
Gynecomastia is the most common male breast disorder. It is not a
tumor but rather an increase in the amount of a man's breast tissue.
Usually, men have too little breast tissue to be felt or noticed. A man
with gynecomastia has a button-like or disk-like growth under his nipple
and areola, which can be felt and sometimes seen. Although gynecomastia
is much more common than breast cancer in men, both can be felt as a
growth under the nipple, which is why it's important to have any such
lumps checked by your doctor.
Gynecomastia is common among teenage boys because the balance of
hormones in the body changes during adolescence. It is also common in
older men due to changes in their hormone balance.
In rare cases, gynecomastia occurs because tumors or diseases of
certain endocrine (hormone-producing) glands cause a man's body to make
more estrogen (the main female hormone). Men's glands normally make some
estrogen, but it is not enough to cause breast growth. Diseases of the
liver, which is an important organ in male and female hormone
metabolism, can change a man's hormone balance and lead to gynecomastia.
Obesity (being extremely overweight) can also cause higher levels of
estrogens in men.
Some medicines can cause gynecomastia. These include some drugs used
to treat ulcers and heartburn, high blood pressure, and heart failure.
Men with gynecomastia should ask their doctors if any medicines they are
taking might be causing this condition.
Klinefelter syndrome, a rare genetic condition, can lead to
gynecomastia as well as increase a man's risk of developing breast
cancer.
Breast cancer general terms
Here are some of the key words used to describe breast cancer.
Carcinoma
This is a term used to describe a cancer that begins in the lining
layer (epithelial cells) of organs such as the breast. Nearly all breast
cancers are carcinomas (either ductal carcinomas or lobular
carcinomas).
Adenocarcinoma
An adenocarcinoma is a type of carcinoma that starts in glandular
tissue (tissue that makes and secretes a substance). The ducts and
lobules of the breast are glandular tissue (they make breast milk in
women), so cancers starting in these areas are sometimes called
adenocarcinomas.
Carcinoma in situ
This term is used for an early stage of cancer, when it is confined to the layer of cells where it began. In breast cancer, in situ
means that the abnormal cells remain confined to ducts (ductal
carcinoma in situ, or DCIS). These cells have not grown into (invaded)
deeper tissues in the breast or spread to other organs in the body.
Ductal carcinoma in situ of the breast is sometimes referred to as non-invasive or pre-invasive breast cancer because it may develop into an invasive breast cancer if left untreated.
When cancer cells are confined to the lobules it is called lobular
carcinoma in situ. This is not actually a true pre-invasive cancer
because it does not turn into an invasive cancer if left untreated.
Invasive (infiltrating) carcinoma
An invasive cancer is one that has already grown beyond the layer of
cells where it started (as opposed to carcinoma in situ). Most breast
cancers are invasive carcinomas, either invasive ductal carcinoma or
invasive lobular carcinoma.
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